Cerebral microvascular endothelial cell Na-K-Cl cotransport

Regulation by astrocyte-conditioned medium

Martha E O'Donnell, A. Martinez, D. Sun

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64 Citations (Scopus)

Abstract

Brain microvascular endothelial cells play an important role in regulation of ion and fluid movement between the blood and the brain interstitium. Astrocytes have been shown to induce blood-brain barrier properties in the endothelial cells, including formation of tight junctions and increased expression and asymmetric distribution of enzymes and ion transport systems. Previous studies have demonstrated that endothelial cells of bovine aorta possess a highly active Na-K-Cl cotransport system that participates in intracellular volume regulation. The present study was conducted to evaluate Na-K-Cl cotransport activity of cerebral microvascular endothelial cells and to determine whether astrocyte-conditioned medium (CM) influences Na-K-Cl cotransport activity of these cells. We found the brain microvascular endothelial cells to exhibit a robust Na-K-Cl cotransport activity, comprising 50% of the total K influx. Activity of the cotransporter was stimulated by agents that elevate intracellular Ca and by hypertonicity and was inhibited by agents that elevate adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, or activate protein kinase C. Exposure of the cells to primary astrocyte- or C6 glial cell-CM but not A7r5 or A10 vascular smooth muscle cell-CM also increased cotransport activity. However, this effect required > 1 h of exposure to CM, was additive with the effects of vasopressin, calcium ionophore, and hypertonicity, and was blocked by the protein synthesis inhibitor cycloheximide. These findings are consistent with the hypothesis that expression of endothelial cell Na-K-Cl cotransport is induced and/or maintained by astrocytes and that the cotransporter may be an important component of blood-brain barrier function.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume268
Issue number3 37-3
StatePublished - 1995

Fingerprint

astrocytes
Endothelial cells
Conditioned Culture Medium
Astrocytes
endothelial cells
Endothelial Cells
Brain
blood-brain barrier
Blood-Brain Barrier
brain
Cells
Ions
protein synthesis inhibitors
guanosine
Protein Synthesis Inhibitors
vasopressin
tight junctions
Calcium Ionophores
Tight Junctions
antineoplaston A10

Keywords

  • aortic endothelial cells
  • bumetanide
  • C6 glial cells
  • cultured cerebral microvascular endothelial cells
  • hypertonicity
  • osmolarity
  • primary astrocytes
  • regulation of intracellular volume
  • regulatory volume increase

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology
  • Agricultural and Biological Sciences(all)

Cite this

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title = "Cerebral microvascular endothelial cell Na-K-Cl cotransport: Regulation by astrocyte-conditioned medium",
abstract = "Brain microvascular endothelial cells play an important role in regulation of ion and fluid movement between the blood and the brain interstitium. Astrocytes have been shown to induce blood-brain barrier properties in the endothelial cells, including formation of tight junctions and increased expression and asymmetric distribution of enzymes and ion transport systems. Previous studies have demonstrated that endothelial cells of bovine aorta possess a highly active Na-K-Cl cotransport system that participates in intracellular volume regulation. The present study was conducted to evaluate Na-K-Cl cotransport activity of cerebral microvascular endothelial cells and to determine whether astrocyte-conditioned medium (CM) influences Na-K-Cl cotransport activity of these cells. We found the brain microvascular endothelial cells to exhibit a robust Na-K-Cl cotransport activity, comprising 50{\%} of the total K influx. Activity of the cotransporter was stimulated by agents that elevate intracellular Ca and by hypertonicity and was inhibited by agents that elevate adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, or activate protein kinase C. Exposure of the cells to primary astrocyte- or C6 glial cell-CM but not A7r5 or A10 vascular smooth muscle cell-CM also increased cotransport activity. However, this effect required > 1 h of exposure to CM, was additive with the effects of vasopressin, calcium ionophore, and hypertonicity, and was blocked by the protein synthesis inhibitor cycloheximide. These findings are consistent with the hypothesis that expression of endothelial cell Na-K-Cl cotransport is induced and/or maintained by astrocytes and that the cotransporter may be an important component of blood-brain barrier function.",
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TY - JOUR

T1 - Cerebral microvascular endothelial cell Na-K-Cl cotransport

T2 - Regulation by astrocyte-conditioned medium

AU - O'Donnell, Martha E

AU - Martinez, A.

AU - Sun, D.

PY - 1995

Y1 - 1995

N2 - Brain microvascular endothelial cells play an important role in regulation of ion and fluid movement between the blood and the brain interstitium. Astrocytes have been shown to induce blood-brain barrier properties in the endothelial cells, including formation of tight junctions and increased expression and asymmetric distribution of enzymes and ion transport systems. Previous studies have demonstrated that endothelial cells of bovine aorta possess a highly active Na-K-Cl cotransport system that participates in intracellular volume regulation. The present study was conducted to evaluate Na-K-Cl cotransport activity of cerebral microvascular endothelial cells and to determine whether astrocyte-conditioned medium (CM) influences Na-K-Cl cotransport activity of these cells. We found the brain microvascular endothelial cells to exhibit a robust Na-K-Cl cotransport activity, comprising 50% of the total K influx. Activity of the cotransporter was stimulated by agents that elevate intracellular Ca and by hypertonicity and was inhibited by agents that elevate adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, or activate protein kinase C. Exposure of the cells to primary astrocyte- or C6 glial cell-CM but not A7r5 or A10 vascular smooth muscle cell-CM also increased cotransport activity. However, this effect required > 1 h of exposure to CM, was additive with the effects of vasopressin, calcium ionophore, and hypertonicity, and was blocked by the protein synthesis inhibitor cycloheximide. These findings are consistent with the hypothesis that expression of endothelial cell Na-K-Cl cotransport is induced and/or maintained by astrocytes and that the cotransporter may be an important component of blood-brain barrier function.

AB - Brain microvascular endothelial cells play an important role in regulation of ion and fluid movement between the blood and the brain interstitium. Astrocytes have been shown to induce blood-brain barrier properties in the endothelial cells, including formation of tight junctions and increased expression and asymmetric distribution of enzymes and ion transport systems. Previous studies have demonstrated that endothelial cells of bovine aorta possess a highly active Na-K-Cl cotransport system that participates in intracellular volume regulation. The present study was conducted to evaluate Na-K-Cl cotransport activity of cerebral microvascular endothelial cells and to determine whether astrocyte-conditioned medium (CM) influences Na-K-Cl cotransport activity of these cells. We found the brain microvascular endothelial cells to exhibit a robust Na-K-Cl cotransport activity, comprising 50% of the total K influx. Activity of the cotransporter was stimulated by agents that elevate intracellular Ca and by hypertonicity and was inhibited by agents that elevate adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, or activate protein kinase C. Exposure of the cells to primary astrocyte- or C6 glial cell-CM but not A7r5 or A10 vascular smooth muscle cell-CM also increased cotransport activity. However, this effect required > 1 h of exposure to CM, was additive with the effects of vasopressin, calcium ionophore, and hypertonicity, and was blocked by the protein synthesis inhibitor cycloheximide. These findings are consistent with the hypothesis that expression of endothelial cell Na-K-Cl cotransport is induced and/or maintained by astrocytes and that the cotransporter may be an important component of blood-brain barrier function.

KW - aortic endothelial cells

KW - bumetanide

KW - C6 glial cells

KW - cultured cerebral microvascular endothelial cells

KW - hypertonicity

KW - osmolarity

KW - primary astrocytes

KW - regulation of intracellular volume

KW - regulatory volume increase

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M3 - Article

VL - 268

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

SN - 1931-857X

IS - 3 37-3

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